import type { Questionnaire, QuestionnaireItem } from 'fhir/r4';

export const QUESTIONNAIRE_HIDDEN_URL = 'http://hl7.org/fhir/StructureDefinition/questionnaire-hidden';

// A scored LOINC instrument ends in an item like `{ text: "Total score", type: "decimal" }` with nothing that
// says it is calculated. Akashic does not score, so a patient would meet an empty box meant to be left blank.
// Never show a number we did not compute: it is hidden (the renderer honours
// questionnaire-hidden, and the builder shows it) and read-only, until scoring exists.
const isUncomputedTotal = (item: QuestionnaireItem): boolean =>
    (item.type === 'decimal' || item.type === 'integer')
    && !item.answerOption?.length
    && /\btotal\s+score\b/i.test(item.text ?? '');

const markItems = (items: QuestionnaireItem[] | undefined): QuestionnaireItem[] | undefined =>
    items?.map((item) => {
        const children = markItems(item.item);
        if (!isUncomputedTotal(item)) return children ? { ...item, item: children } : item;
        const others = (item.extension ?? []).filter((extension) => extension.url !== QUESTIONNAIRE_HIDDEN_URL);
        return {
            ...item,
            readOnly: true,
            extension: [...others, { url: QUESTIONNAIRE_HIDDEN_URL, valueBoolean: true }],
        };
    });

export const hideUncomputedTotals = (questionnaire: Questionnaire): Questionnaire => ({
    ...questionnaire,
    ...(questionnaire.item ? { item: markItems(questionnaire.item) } : {}),
});